Because the elevated temperature conditions to which woven or knit textile fabrics are usually subjected during wet processing can have a significant physical effect on the fiber of which the fabrics are formed, it is common practice to employ a preliminary heat treatment whenever such an effect is expected. In the case of textured goods the effect of heat is one of bulking as a result of heat induced recovery of texture in the fiber that has been subdued or diminished in the course of fabric formation. If this bulking is not induced preliminarily, it will take place during wet processing and where such processing includes dyeing an uneven strike or coloring effect is virtually certain to result. In addition, many fabrics are subject to pronounced shrinkage during wet processing and must be heat treated preliminarily in order to provide adequate dimensional stability for suitable finishing. The latter effect often occurs in cotton and woolen goods and blends thereof.
According to prior practice, heat treatment of textile fabrics for prebulking or preshrinking has commonly been carried out either in a heated tumbling drum or a loop washer arrangement, both of which have imposed burdensome fabric handling problems. The present invention provides for such heat treatment in an exceptionally simple and effective manner.